Volumetric three-dimensional recognition of biological microorganisms using multivariate statistical method and digital holography

We present a new statistical approach to real-time sensing and recognition of microorganisms using digital holographic microscopy. We numerically produce many section images at different depths along a longitudinal direction from the single digital hologram of three-dimensional (3D) microorganisms in the Fresnel domain. For volumetric 3D recognition, the test pixel points are randomly selected from the section image; this procedure can be repeated with different specimens of the same microorganism. The multivariate joint density functions are calculated from the pixel values of each section image at the same random pixel points. The parameters of the statistical distributions are compared using maximum likelihood estimation and statistical inference algorithms. The performance of the proposed system is illustrated with preliminary experimental results.

Real-time automated 3D sensing, detection, and recognition of dynamic biological micro-organic events

In this paper, we present an overview of three-dimensional (3D) optical imaging techniques for real-time automated sensing, visualization, and recognition of dynamic biological microorganisms. Real time sensing and 3D reconstruction of the dynamic biological microscopic objects can be performed by single-exposure on-line (SEOL) digital holographic microscopy. A coherent 3D microscope-based interferometer is constructed to record digital holograms of dynamic micro biological events. Complex amplitude 3D images of the biological microorganisms are computationally reconstructed at different depths by digital signal processing. Bayesian segmentation algorithms are applied to identify regions of interest for further processing. A number of pattern recognition approaches are addressed to identify and recognize the microorganisms. One uses 3D morphology of the microorganisms by analyzing 3D geometrical shapes which is composed of magnitude and phase. Segmentation, feature extraction, graph matching, feature selection, and training and decision rules are used to recognize the biological microorganisms. In a different approach, 3D technique is used that are tolerant to the varying shapes of the non-rigid biological microorganisms. After segmentation, a number of sampling patches are arbitrarily extracted from the complex amplitudes of the reconstructed 3D biological microorganism. These patches are processed using a number of cost functions and statistical inference theory for the equality of means and equality of variances between the sampling segments. Also, we discuss the possibility of employing computational integral imaging for 3D sensing, visualization, and recognition of biological microorganisms illuminated under incoherent light. Experimental results with several biological microorganisms are presented to illustrate detection, segmentation, and identification of micro biological events.

Shape tolerant three-dimensional recognition of biological microorganisms using digital holography

We present a system for shape tolerant three-dimensional (3D) recognition of biological microorganisms using holographic microscopy. The system recognizes 3D microorganisms by analyzing complex images of the 3D microorganism restored from single-exposure on-line (SEOL) digital hologram. In this technique the SEOL hologram is recorded by a Mach-Zehnder interferometer, and then the original complex images are reconstructed numerically at different depths by inverse Fresnel transformation. For recognition, a number of sampling segment features are arbitrarily extracted from the restored 3D image. These samples are processed using a number of cost functions and the sampling distributions for the difference of the parameters (location, dispersion) between the sample segment features of the reference and input 3D image are calculated using a statistical sampling method. Then, a hypothesis testing for the equality of the parameters between reference and input 3D image is performed for a statistical decision about populations on the basis of sampling distribution information. Student's t distribution and Fisher's F distribution are used to statistically analyze the difference of means and the ratio of variances of two populations, respectively. The proposed system is designed to be tolerant to recognizing various, plain microorganisms with analogous shape such as bacteria and algae. Preliminary experimental results are presented to illustrate the robustness of the proposed recognition system using statistical inference.

Three-dimensional imaging and recognition of microorganism using single-exposure on-line (SEOL) digital holography

We address three-dimensional (3D) visualization and recognition of microorganisms using single-exposure on-line (SEOL) digital holography. A coherent 3D microscope-based Mach-Zehnder interferometer records a single on-line Fresnel digital hologram of microorganisms. Three-dimensional microscopic images are reconstructed numerically at different depths by an inverse Fresnel transformation. For recognition, microbiological objects are segmented by processing the background diffraction field. Gabor-based wavelets extract feature vectors with multi-oriented and multi-scaled Gabor kernels. We apply a rigid graph matching (RGM) algorithm to localize predefined shape features of biological samples. Preliminary experimental and simulation results using sphacelaria alga and tribonema aequale alga microorganisms are presented. To the best of our knowledge, this is the first report on 3D visualization and recognition of microorganisms using on-line digital holography with single-exposure.

Non-association of estrogen receptor genotypes with bone mineral density and bone turnover in Korean pre-, peri-, and postmenopausal women

Estrogen is known to play a critical role in both skeletal maturity and the rate of bone loss. This suggests the possibility that the estrogen receptor (ER) gene is one of the candidate genes that determines peak bone density and/or bone turnover rate. We investigated two established restriction fragment length polymorphisms (RFLPs) in intron 1 at the ER gene, represented as PvuII and XbaI. In 598 healthy Korean women aged 20-74 years, we examined the association of these ER genotypes with bone mineral density (BMD) and bone turnover status. The distribution of the PvuII and XbaI RFLPs was as follows: pp 205 (34.3%), Pp 308 (51.5%), PP 85 (14.2%) and xx 384 (64.2%), Xx 180 (30.1%), XX 34 (5.7%), respectively (where capital letters signify the absence of, and lower-case letters signify the presence of, the restriction site of each RFLP). No significant genotypic differences were found in BMD and bone markers. We grouped the subjects into three categories according to their menstrual status: 104 premenopausal women with regular menstruation, 182 perimenopausal women who had amenorrhea of not less than 3 months and not more than 12 months' duration, and 312 postmenopausal women whose last menstruation was at least 12 months previously. No significant genotypic difference in either BMD or bone markers was found in any of these three groups. Furthermore we categorized women in peri- and postmenopause into a high loser group and a normal loser group according to the level of bone resorption markers. There was no difference in genotypic proportions between the high and normal loser groups. Our data suggest that these ER polymorphisms are not associated with BMD or bone turnover in Korean women.

Assessment of UK practice for management of acute childhood idiopathic thrombocytopenic purpura against published guidelines

BACKGROUND

Guidelines for management of acute immune thrombocytopenic purpura (ITP) in childhood were published in 1992. Regional audit in 1995 showed substantial variation in clinical practice not related to clinical differences in patient groups, which indicated a need for national audit.

METHODS

Individuals aged from birth to their 16th birthday newly presenting with ITP were identified over 14 months by regular mailing of paediatricians and haematologists for case notification. Information was obtained from follow-up by a detailed questionnaire.

FINDINGS

ITP was clinically mild and benign in 323 (76%) of 427 cases, including 181 (70%) of 260 cases with platelet counts below 10 x 10(9)/L. There were no deaths or intracranial haemorrhages. There was a substantial discrepancy between clinical practice and published guidelines: many children were admitted to hospital and received treatment unnecessarily; there was overuse of intravenous immunoglobulin (IVIg) as first-line therapy (94 children); children received steroids without marrow examination; and there was inappropriate use of platelet transfusions (41 with mild or moderate disease).

INTERPRETATION

Our results indicate a need for change in practice.